Item and State questions

I have been puzzling over this one for a long time now, and I can't seem to think of a way to make it work. Hopefully, someone here will be able to help.

What I want: Using RPG Maker XP, I would like to design an item that makes the user "immortal" for several turns. During this period they should be immune to damage and status effects. However, after the set number of turns passes(let's say after 5 turns) the item wears off and the character is instantly KO'd.

Here's what I tried: I made the item induce a state that I named "Death Delay" upon the character. I set the state to wear off after 5 turns, or after the battle ends. I tried setting the state to "regard as 0HP", but this does three things that I don't like; (1)the chacter's battler fades away, (2)the character can no longer use skills, and (3)after the state wears off, the battler will reappear and the character will be left with 1HP, not zero. I'm not sure how else to approach this. I need to fix it so that the character is KO'd completely when the state fades away, and the battler should not disappear before then. It would also be nice if the enemy would continue to attack the character, which does not happen under "regard as zero HP." This is preferable, but not needed.

What I need from you: I'm sure this would be possible with scripts, but I would like to avoid that at all costs, as I am a total noob at using them and would surely screw things up. Maybe if the item triggers a common event? I don't know... Any help would be greatly appreciated. Even if you have just a random idea, please speak up. It might help me think of something...

Okay, I may have found a way to get the thing working. I will gladly post more info on this item-thing down the road when I polish it up a bit.

However, I still need to find a way to make the actor immortal. Can it be done? If so, how? I'm sure it's possible, but I just can't figure it out. This is what I really need your help on right now. Feel free to attempt to tackle the entire problem as mentioned in my original post if you're up to the challenge, but it's not necessary anymore. Just make me immortal.